1. Field of the Invention
The present invention relates to a semiconductor device and method of manufacturing the same, and more particularly to a semiconductor device including copper (Cu) used as wiring material and method of manufacturing the same.
2. Description of the Related Art
Copper (Cu) wiring can reduce the parasitic resistance and the parasitic capacity lower than aluminum wiring and accordingly becomes more important as wiring material and via material in a semiconductor device. Different from aluminum (Al) and so forth, however, Cu is difficult to be processed by etching and accordingly the so-called damascene technology is applied for wiring and via formation (For example, see JP-A 8-222569). In a word, processes of photolithography and etching are applied to form a trench in an interlayer insulator for burying Cu wiring therein. A process of CVD (Chemical Vapor Deposition) is then applied to form a barrier metal film composed of a silicon nitride (SiN) over the entire surface of the interlayer insulator including the interior of the trench. Thereafter, a process of spattering or plating is applied to form a Cu film over the entire surface of the silicon nitride including the interior of the trench. Subsequently, CMP (Chemical Mechanical Polishing) is executed to remove Cu from the outside of the trench to form Cu wiring. The above-described barrier metal film is formed to prevent copper from diffusing into the interlayer insulator and degrading the insulation of the interlayer insulator.
In the above semiconductor device and method of manufacturing the same, however, when CMP is executed to remove Cu from the outside of the trench, a chemical reaction resulted from the CMP slurry produces the so-called battery effect between the barrier metal film and the Cu film. As a result, the barrier metal film and/or the Cu film of upper end of the trench melt, and produce a recess as a problem. This recess increases the wiring resistance and the via-hole resistance and reduces the characteristic of Cu wiring, or a low resistivity. It also causes a problem deteriorating the reliability of wiring. In the future, as fine patterning of semiconductor devices increasingly proceeds, the increase in resistance due to the melt is expected to become increasingly serious.